Apparatus for developing photographic materials

ABSTRACT

Photographic elements are immersion developed with imagedependent agitation of the developer relative to the element surface. Development releases negatively charged waste particles that congregate adjacent the image areas. A negatively charged electrode in the developer tank electrolyzes the developer releasing a uniform stream of fine hydrogen bubbles. This electrode is situated so that the bubbles gently scrub the face of the element, dislodging the waste particles. A positively charged electrode attracts the particles, permitting fresh developer to reach developing image areas.

United States Patent [1 1 Lasky APPARATUS FOR DEVELOPING PHOTOGRAPHIC MATERIALS Inventor: Daniel J. Lasky, Wappingers Falls,

Assignee: International Business Machines Corporation, Armonk, NY.

Filed: June 30, 1971 App]. No.: 158,563

Related US. Application Data Division of Ser. No. 744,405, July 12, 1968, Pat. No. 3,615,515.

US. Cl. ..95/89 R, 204/299 R Int. Cl. ..G03d 3/04 Field of Search ..95/89 R, 94 R, 96,

References Cited UNITED STATES PATENTS 8/1944 Rzymkowski ..9s s9 R ux 11 3,733,993 1 May 22, 1973 3,508,483 4/1970 Weider et al. ..95/96 3,440,160 4/1969 Matkovich ..204/299 R X Primary Examiner-Samuel S. Matthews Assistant Examiner-Fred L. Braun Attorney-A. Sidney Alpert et al.

[57] ABSTRACT Photographic elements are immersion developed with image-dependent agitation of the developer relative to the element surface. Development releases negatively charged waste particles that congregate adjacent the image areas. A negatively charged electrode 'in the developer tank electrolyzes the developer releasing a uniform stream of fine hydrogen bubbles. This electrode is situated so that the bubbles gently scrub the face of the element, dislodging the waste particles. A positively charged electrode attracts the particles, permitting fresh developer to reach developing image areas.

7 Claims, l3-Drawing Figures I'll PUMP

FIXER /74 CONTROLLER PATENTEDNIYZZIOB SHEET 2 DE 2 INTRODUCE FIXER mm TANK W I DRAIN DEVELOPER REMOVE TO DRYER PLATE,TAKE

APPLY VOLTAGE TO ELECTRODES AT 30 SEC INTERVALS FOR 15 SEC CONTINUOUS WATER RINSE LOAD PLATE IN TANK DRAIN FIXER FIG.

INTRODUCE DEVELOPER INTO TANK FIG. 8

DEVELOPER F I G. 1 3

FIXER RINSE ELECTRODE VOLTAGE ,1 R R E T -LL VA NAU R BD L W RDI NCL D RR s m A A W N RT ll DR A H E C T mPUA UR Aw Drr. REMP NOVA D R T F E I AN '8 RT D H CE E HMR \I VIG N AC C II PTT MT M EL N A A A0 .IT CL V AN R M D I I R ER CE Tl un U AW WDD W A 0 EL mR N L T II B E AN m R D D a G R MMR N HF. ELD III T I ADOT T RRR F Dn DA W w HN 1 APPARATUS FOR DEVELOPING PHOTOGRAPHIC MATERIALS This application is a division of application Ser. No. 744,405 filed July 12, 1968, now U.S. Pat. No. 3 ,615 ,5

BACKGROUND OF THE INVENTION The present invention relates generally to the field of photographic processing, and more particularly to improved apparatus and methods of developing exposed photographic emulsion layers which are carried, for example, on glass plates or film strips.

The role of photography in the micro-electronics or printed circuit industry has taken on new dimensions as the industry has expanded. Printed circuit technology is ever posing greater demands upon photography, requiring, for example, photographic master patterns for producing etched circuits having line width tolerances held to previously unattainable limits. The tolerance problem is critical since inaccuracies of the master patterns are reflected by magnified'inaccuracies on the circuit boards. The workers in the photographic arts have responded to these demands by building automatic processors that have, in certain functions, virtually replaced manual photographic processing techniques. These automatic processors are good, but as yet are not good enough for high-quality, closetolerance work, e.g., where line widths on a master pattern plate or film strip must be uniformly held to one thousandth of an inch.

A brief summary of photographic processing will quickly point out some of the difficulties in close tolerance developing. The conventional photographic processing involves first subjecting an exposed photographic element having an emulsion layer that contains, for example, silver halide grains, to a developing bath and thereafter to fixing and washing baths. The mechanism of the most common developingreaction, i.e., the so-called chemical process, involves the reduction of silver ions to metallic silver by a suitable reducing solution or developer. As developing occurs (which is, in fact, an oxidation-reduction mechanism), negatively charged waste particles are released into the developer, such as chloride, bromide, or idoized salts. These salts accumulate adjacent the exposed areas of the emulsion layer and repress or inhibit development by preventing the access by additional, fresh developer to the exposed areas. This condition is unacceptable as it leads to non-uniform development, and thus leads to non-uniformity in line width in the pattern developed on the photographic element. The condition has been alleviated, in part, by the use of various agitation arrangements that attempt to convey fresh developer to the exposed areas of the emulsion layer.

It has been found that agitation of the developer during the development mechanism is necessary for a controlled process. In the prior art, the agitation arrangements have conventionally taken the form of either a mechanical paddle wheel assembly that agitates the entire developer bath, or a nitrogen bubble system for 10- calized agitation adjacent the exposed areas of the emulsion layer. These arrangements are well known in the prior art, and are commonly regarded as the most controllable of the available agitation systems. However, even the best of these prior art arrangements does not differentiate between an area of the emulsion layer that calls for more fresh developer and an area that needs little or no further development. This leads to non-uniformity in the development and, as noted above, ultimately results in variations or nonuniformity in line widths. Further, while the conventional agitation arrangements are intended to, and do displace a majority of the waste particles from their initial locations adjacent the exposed emulsion surfaces, in many cases the waste particles are permitted to recirculate through the developer, causing a generalized exhaustion of the developer. Further, the particles may fall to the floor of the developer tank tending to clog the agitation system.

Accordingly, it is a general object of the present invention to provide apparatus and methods intended to overcome these above mentioned problems in prior art photographic development processors.

It is a more specific object of the present invention to provide apparatus and methods that permit uniform development of exposed areas of a photographic emulsion layer and thereby produce essentially uniform patterns having uniform line widths on photographic elements.

A further object of the present invention resides in the provision of a photographic development process that utilizes electrophoresis and electrolysis to obtain non-mechanical, and image dependent agitation of a developer bath.

Additional objects of the invention include, but are not limited to the provision of apparatus and methods for photographic processing that:

1. permit single tank processing of photographic elements without necessitating the removal of the elements prior to completion of the last process step;

2. are equally compatible to black and white or color processing;

3. are relatively simple in operation and inexpensive to build and operate; and

4. do not present a safety hazard to operating personnel.

SUMMARY OF THE INVENTION I provide, in one form of the invention, a processing tank in which an exposed photographic element is subjected successively to various treating baths or solutions. In this regard, a controller operates fluid pumps to introduce, in timed succession, a developer, a fixer and a water bath into the tank containing the exposed photographic element.

The processing tank is arranged, in one embodiment, to receive a plate hanger in which is mounted a photographic plate having an exposed emulsion layer. Mounted in the tank on the side of the plate adjacent its exposed emulsion layer is an electrode screen or grid that is connected to a source of positive DC. potential. Also mounted in this tank, adjacent the lower end of the plate hanger, is a second electrode that extends across the width of the plate hanger. This second electrode is connected to a source of negative D.C. potential.

When the developing solution is introduced into the tank with an exposed plate therein, an oxidationreduction reaction between the developer and exposed emulsion layer produces negatively charged particulate waste products that congregate or collect in a location immediately adjacent the exposed or image areas of the emulsion layer. This precludes fresh developer from approaching the exposed areas inhibiting development.

As explained previously, this phenomena is familiar to those skilled in the art.

In the prior art, these waste particles are variously termed oxidation products or non-metallic salts. In the exemplification, the particles are quinone sulphonate. Under influence of the controller, positive D.C. potential of a pre-selected magnitude is applied to the electrode screen and negative DC potential of a preselected magnitude is applied to the second electrode. The second electrode electrolyzes the developer, releasing fine hydrogen bubbles that rise upwardly across the face of the emulsion layer. These bubbles cause agitation as they reach the waste particles, effectively breaking free or dislodging the particles from their initial locations adjacent the exposed areas of the emulsion layer. Simultaneously, the positively charged electrode screen attracts the negatively charged waste particles, and the particles move toward the electrode screen permitting fresh developer to replace them adjacent the exposed emulsion areas. In this manner, additional fresh developer reaches the exposed emulsion areas in proportion to the removal of waste products therefrom, providing, in effect, image controlled agitation of the developer.

The advantages of the above described invention are many. In part, the'arrangement is relatively simple, requiring no moving parts, external mechanical drives or compressed nitrogen supplies as necessitated by the prior art agitation arrangements. Additionally, there is no recirculation of the waste particles within the developer, as the particles are eventually collected on the electrode screen. This inhibits exhaustion, and increases the useful life of the developer. The invention achieves consistently developed patterns with precise, uniform line widths at a yield heretofore unavailable with known prior art agitation arrangements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view, partially in perspective and partially in schematic, illustrating one preferred form of the apparatus used in the practice of the present invention;

FIG. 2 is an enlarged partial vertical sectional view taken substantially on the plane of line 2-2 in FIG. 1;

FIG. 3 is still further enlarged and partially schematic cross section of a portion of the apparatus illustrated in FIG. 2;

FIG. 4 is a front elevational view of a representative master plate produced in accordance with the present invention;

FIG. 5 is an enlarged view of a portion of the face of the plate shown in FIG. 4, illustrating the uniformity in line width achieved by means of the present invention;

FIG. 6 is a view similar to that of FIG. 5 showing the type of line variations or non-uniformity occurring in plates developed by prior art apparatus;

FIG. 7 is a block diagram that, taken in conjunction with FIG. 8, further explains the steps that take place in a preferred process comprising an aspect of this invention;

FIG. 8 is a timing diagram that, taken in conjunction with FIG. 7, further explains the steps that take place in a preferred process comprising an aspect of this invention;

FIG. 9 is another block diagram also showing a series of steps used to practice the present invention; and

FIGS. 10, 11, 12 and 13 illustrate in perspective and cross section a second preferred form of the apparatus comprising an aspect of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specifically to the drawings and particularly to FIGS. 1, 2 and 3, I have shown one form of the apparatus used in the practice of my invention. The apparatus includes an insulative processing tank generally denoted by reference numeral 10 that is of generally rectangular shape. The tank 10 is adapted to receive a plate carrier shown in phantom line in FIG. 1 and designated by numeral '12. The carrier 12 comprises a frame 14 having an upwardly extending handle 16 that permits easy transport of the carrier. The carrier 12 has mounted therein a photographic plate 18 as shown in FIG. 2. In the exemplification, the plate is an Ortho Type III glass plate generally used in printed circuit fabrication to produce master patterns. The plate 18 has the usual emulsion layer 20 on one face, as shown in exaggerated fashion in FIG. 3 for purposes of illustration. In practice, the emulsion layer, which normally carries silver halide grains, is exposed either manually or by a conventional automatic art work generator such as the well known numerically controlled Gerber 500 Artwork Generator. A representative plate is shown in FIG. 4 as having 8 frames with preselected patterns. As will be noted, frame 22 has horizontal lines and frame 24 has vertical lines. In actual practice, the pattern includes a plurality of parallel lines 26 that are 0.002 inch wide with 0.002 inch spacing therebetween, and one or more 0.125 inch lines 28. A pair of channels or grooves 46 and 48 for accommodating the frame 14, permit the frame 14, carrying the plate 18 to be readily mounted in and/or removed from the tank 10.

It is important that the lines 26 and 28 be extremely uniform in width throughout their length and that the spaces therebetween be precise, e.g.; "0.00l inch toler' ance. This is because the developed plates are used as master patterns in the production of printed circuit boards, as for example, by well known photographic etching techniques. It is well known that variations in line widths on the master plate will generate even greater variations in line widths on the finished printed circuit board or element, which is intolerable as line width variations on the printed circuit board result in variations in electrical parameters.

In order to provide an agitation system that will ultimately result in the production of uniform lines on plate 18, in accordance with the invention, there is mounted in the tank 10 a first electrode 30 by mounting means such as screws 32. The electrode 30 shown in the exemplification is, in the actual practice of the invention, a platinum plated titanium screen having a rather fine mesh. This type electrode is used as it has proved to be quite resistant to the acidic and basic solutions introduced into the tank 10 during processing. However, it is contemplated that other suitable electrode configurations could be used, for example platinum expanded plates or screens or the like. As will be seen in FIGS. 1-3, the electrode 30 is mounted in parallel relationship to the major walls 34 and 36 of tank 10, and is closely adjacent wall 36. In addition, it will be seen that the electrode 30 parallelsplate 18 when the plate is in place in tank 10. In thecase of the actual tank that I use to practice my invention, a spacing between the plate l8 and electrode 30 of approximately 1 inch was used since the results were found to be most satisfactory at this distance. However, it is contemplated that the spacing between plate 18 and electrode 30 could be varied between 1/16 and 1% inches, according to the materials used, etc. In actual practice, the dimensions of the tank 10 are as follows; width, approximately 2l.5 inches, depth, approximately 2.7 inches and height approximately 24.5 inches. A tank this size will accommodate photographic plates up to 16 by 20 inches. The tank body must be constructed of electrically insulated material, and l constructed the tank of Plexiglas, althoughother materials could obviously be used.

Also mounted in the tank 10, and generally adjacent the lower end of the plate 18 when it is in place in the tank 10, is a second electrode 40. Electrode 40 is spaced slightly away from the lower wall 42 of the tank, and extends somewhat past the emulsion layer 20 of plate 18. The second electrode 40 is mounted on tank wall 34, and as will be seen in FIGS. 2 and 3 has a raised ridge 44 terminating in an edge that lies in a plane generally parallel and in close proximity to the face of emulsion layer 20. Of course, the electrode 40 extends approximately the full width of the tank 10 underlying plate 18. In actual practice, electrode 40 is a stainless steel plate having dimensions of approximately 1% by 20% by inches.

In the preferred embodiment, schematically shown in FIG. 1, black and white photographic elements such as the plate 18 may be processed. In this regard, a developer or developing agent 50 is contained in a service tank 52 and a fixer or fixing agent 54 is contained in another service tank 56. A hose or conduit 58 connects tank 52 to a developer pump 60 and another hose or conduit 62 connects tank 56 to a fixer pump 64. The pumps 60 and 64 are connected by conduits 66 and 68 respectively to a manifold 70 that opens into the interior of processing tank 10. Also connected to the manifold 70 is a conduit 72 that is connected to a water sup-- ply solonoid 74 which is in turn connected to a suitable water supply (not illustrated). As will be appreciated, the tanks 52, 56 and the water supply are used to introduce the developer 50, the fixer 54 and water into the tank 10.

Since it is desireable to obtain automated and'consistent control of the above apparatus, I have provided a controlling means or controller generally denoted by reference numeral 78. Controller 78 is connected by electrical leads 80, 82, 83 and 84 to a D.C. power supply 86, to the developer pump 60, to the solonoid 74 and to fixer pump 64 respectively. In practice, the controller 78 comprises a cylindrical drum that is rotated at a constant speed to activate microswitches. Arrangements of this type well known to those skilled in the art as Program Drums." It will be appreciated, however, that any suitable control means for operating electrical devices such as the pumps 60 and 64 and the solonoid 74 may be utilized for this purpose. The purpose, of course, is to operate the pumps 60 and 64 in timed sequence to introduce the developer 50 and the fixer 54 into the tank 10 and to introduce water into the tank thereafter.

In order to drain the tank 10, I have provided three outlet hoses or conduits 88, 90 and 92 communicating with the interior the tank 10 and leading to a manifold 94. The manifold 94 in turn is connected by conduit 96 to a suitable drain pump 98 that is also operated by the controller 78, connected thereto by electrical lead 100. Having now described the physical characteristics of the apparatus shown in FIGS. 1, 2 and 3, I will describe the operation of and mechanisms associated with my invention. As known to those skilled in the art, when an exposed photographic element is placed in a developer, the exposed or image areas of the emulsion, that contain exposed silver halide grains, are converted to metallic silver by a reduction-oxidation mechanism. The developer is oxidized, and, as development commences, there is an accumulation of salts in solution. In the exemplification, since I use in one application a hydroquinone developer such as Kodalith, a developer sold by the Eastman Kodak Company under that name, the salt that is freed is quinone sulfonate. As I have shown in FIG. 3, the quinone sulfonate takes the form of small negatively charged particles generally designated by reference numeral 104. The particles 104 accumulate adjacent exposed or image areas 106 and 108 of the emulsion layer 20 in proportion to the size (or width) of the image area. I have found that if these particles are permitted to remain adjacent the image areas of the emulsion layer 20, they impede development.

In order to permit uniform development of the image areas 106 and 108, I provide the electrodes 30 and 40. The electrode 30 is connected by electrical lead 110 to a positive source of D.C. potential in power supply 86, and the electrode 40 is connected by lead 1 12 to a negative source of D.C. potential in the power supply. The electrode 40, when energized, electrolyzes the developer to produce or generate hydrogen bubbles 120. The bubbles occur uniformly across the width of electrode 40 flowing upwardly from the edge of ridge 44 in a plane closely adjacent the face of plate 18 that carries the emulsion layer 20. The gaseous hydrogen bubbles are fine (approximately one twenty-fifth the size of bubbles generated by nitrogen bubblers) and evenly and closely spaced, and thereby avoid the major objection to nitrogen-bubblers; i.e., large bubbles that are too widly spaced apart. In operation, when the negatively charged waste particles 104 begin to accumulate adjacent their exposed image areas 106 and 108, the electrodes 30 and 40 are energized. Bubbles thereby scrub the emulsion face, breaking loose or dislodging the particles 104. Simultaneously, electrode 40 attracts the particles 104, drawing them away from their initial locations adjacent the image areas. This permits additional, fresh developer to displace the particles adjacent the image areas, thereby permitting development to continue. The agitation resulting from this combination of electrolytic action accomplished by electrode 40 and electrophoretic action accomplished by electrode 30 is responsive to the number of particles generated, and thus may be termed Image Controlled Agitation." In this regard, the amount of fresh devel oper that can approach the image areas is dependent upon the number of waste particles 104 drawn away for their initial locations.

It may now be asked why I have taken such pains to move the waste particles 104 away from the photographic plate 18 and why it is important for this to be accomplished in an image controlled manner. I have shown a representative type of photographic platewith a master pattern thereon in FIG. 4, and what two of the 2 mil (0.002 inch) lines look like when the plate has been developed using the apparatus of this invention (FIG. and by the prior art apparatus (FIG. 6). As previously mentioned, the representative pattern has a plurality of 2 mil horizontal and vertical lines and one or more 125 mil lines. The majority of the developed 2 mil lines appear as shown in FIG. 6 when conventional apparatus is used to agitate the developer. That is, the lines and the spacings therebetween are irregular and non-uniform. This is because the prior art apparatus is incapable of differentiating between an image area that calls for more fresh developer and an image area that needs little or no development. It will be understood that more developer is needed adjacent the 125 mil lines than is needed adjacent the 2 mil lines, and that the prior art apparatus is not responsive to this difference. What actually happens using the prior art paddle wheel is that sufficient stirring of the entire developer bath to supply the large image areas 106 with an adequate supply of fresh developer will cause the smaller image area 108 to be overdeveloped, and vice versa. In the prior art nitrogen bubble systems, the large, spread apart bubbles displace the waste particles irregularly across the image areas on the plate, leading to variations in development. This leads to the type of developed line as shown in FIG. 6, where portions 107 of the line between bubbles are underdeveloped and hence neck down, while other portions are overdeveloped and hence are too wide.

On the other hand, the uniformity of development, and hence line width that I am able to achieve by the use of the present invention is shown in FIG. 5. Not only is the developed line 26 of FIG. 5 uniform, but I am able to achieve uniformity of spacing between lines and even development of both wide (125 mil) and narrow (2 mil) lines. I have thus been able to surpass the tolerance requirements for the master plates, as well as being able to achieve remarkable consistency between plates.

Referring now to FIGS. 7 and 8, I have shown the steps and a timing diagram of the process as practiced in one preferred fashion using the apparatus of FIG. 1. Under the operation of controller 78, a developer (e.g., Kodalith) is initially introduced into the tank 10 by developer pump 60. The plate carrier 12 carrying an exposed plate 18 is loaded into the tank 10 by sliding it into channels 46 and 48. The negatively charged waste particles 104 immediately-begin to collect or congregate adjacent image areas such as 106 and 108 as the oxidation-reduction mechanism of development occurs. Without some agitation, the particles 104 will remain suspended adjacent the image areas until they gradually sink to the bottom of tank 10. Accordingly, while the developer is in the tank, i.e., for approximately 3 minutes as required for Kodalith developer, approximately 6 volts DC. is applied to electrodes 30 and 40 at 30 second intervals for second durations. This permits uniform development to occur. After the 3 minute development and agitation period, the controller 78 energizes pump 98 to drain the developer from the tank, with drainage taking approximately 15 seconds. When the tank is drained, the controller 78 turns pump 98 off and turns pump 64 on, filling the tank 10 with a suitable fixer 54. The fixer 54 is permitted to remain in the tank for 3 minutes, after which controller 78 again actuates pump 98 to drain the fixer from tank 10. When the tank is drained, controller 78 actuates water supply solenoid 74, permitting fresh water to continuously enter the tank 10 and flow over the tank top for 7 minutes. At this time, controller 78 turns solenoid 74 off and again activates pump 98 to drain the tank of water. This concludes the processing of plate 18, and the carrier 12 is removed from tank 10. The plate 18 will normally then be taken to a dryer.

As will be understood by the previous description of the process, the developing, fixing, and wash cycling takes place in the single tank 10. This is quite advantageous since it minimizes processing errors, and also minimizes safety hazards since the glass plate is not handled during processing. In addition, this eliminates the requirements for several processing tanks, thereby conserving space in the dark room, and the controller '78 insures that the time cycles are extremely accurate.

While I have described the invention in conjunction with FIGS. 1-3, I have actually reduced to practice a second embodiment of the invention wherein I used only electrophoretic action to agitate the developer; i.e., using only the electrode 30 for drawing waste particles 104 away from the image areas I was able to accomplish this by applying approximately 26 volts positive DC. potential to electrode 30 while also providing a ground within the tank. In this regard, I used a ground connection to a plate frame similar to frame 14, except that it was conductive. I was, in this manner, able to effectively develop the image areas of the exposed photographic element with accuracy of line width as in the first embodiment described above. The remaining steps of this process are the same, with the only difference in this second embodiment being the absence of electrode 40 and a higher voltage being applied to electrode 30 to overcome the inertia of particles 104 and draw them toward electrode 30.

It will occur to those skilled in the art that the present invention, as explained so far, has related to black and white film processing, whereas the invention is also equally applicable to both color and reversal processing. Accordingly, in FIG. 9, l have shown one of several processes that I have performed in a single tank similar to tank 10, having electrodes such as electrodes 30 and 40. Of course, it is necessary to add additional service tanks to contain a stop bath, a hardner, and a bleach, and to include pumps therefor. This also requires that the program in controller 78 be changed to control such additional pumps as are needed to practice a color or a reversal process. Therefore, as should be understood, in the process shown in FIG. 9, electrophoretic and electrolitic agitation take place during developing, and all the process steps take place in a single tank.

Referring now specifically to FIG. 9, I have shown a process for developing Ektacolor film, using the well known Kodak C-22 developer and a conventional stop bath, hardener, bleach and fixer all of which are usually specified for use with Ektacolor photographic ele ments. Initially, a photographic plate is loaded into a tank such as tank 10 and washed with water. The water is thereafter drained, and the developer introduced into the tank. As explained above, negatively charged waste particles immediately begin to collect adjacent the image areas, and therefore voltage is applied to the two electrodes in the tank at thirty second intervals for 15 second duration while the developer is in the tank. The developer is then drained and stop bath is introduced into the tank under influence of a controller. After a pre-selected period, the stop bath is drained and the hardener introduced into the tank, the hardener drained and water again introduced into the tank. The water is then drained, a bleach introduced, the bleach drained and water again introduced. After the water is again drained a fixer is introduced into the tank, the fixer drained and the plate is rinsed continuously with the water flowing over the top as explained above. This process has all the advantages mentioned above in conjunction with black and white processing, and additionally has the advantage of replacing several or more separate operations as all the processing steps take place in a single tank.

The previous embodiments of the invention have been explained in conjunction with a generally rectangular tank that accommodates glass plate type photographic elements. I can, by the present invention, also automatically process sheet film using electrophoretic and electrolytic action as explained above. Accordingly, I have shown another embodiment of the invention in FIGS. 10-13 for accomplishing sheet or strip film processing.

The apparatus shown in FIGS. 10-13 achieves exentially the same benefits as that illustrated in the above described embodiments. While the type of photographic element to be handled by this apparatus differs, electrophoretic and electrolytic agitation is still applied. The developing apparatus, generally designated by reference numeral 150 comprises a processing tank 152 that, as will be seen in FIG. 11., is of a cylindrical shape. The tank 152 has a center mounting post or spindle 154 that is adapted to receive the hub 156 of a film carrier spool 158. The tank 152 has an enlarged hollow base 160. As is the case with tank 10, the tank 150 and its base 160 are composed of electrically insulative material, such as the well-known Plexiglas. Connected to the base 160,.and communicating with the interior of base 160 and tank 150 are four conduits or hoses 162, 164, 166 and 168. These conduits perform a similar function as the conduits 66, 68, 72 and 96 as shown above and explained in conjunction with FIG. 1. Thus, for example, conduit 162 may be connected to a developer tank, conduit 164 may be connected to a fixer tank, conduit 166 may be connected to a water supply and conduit 168 may be connected to a pump and drain. n the floor of the base is an electrically conductive annular plate 170 seated around the post 154,. Plate 170, in the exemplification, is a stainless steel plate, and as shown schematically, is connected by lead 172 to the negative side of a DC. power supply (not illustrated).

The spool 158 has two end flanges 174 and 176, connected by hub 156 that has an opening 157 extending therethrough. The flange 174 and the hub 156 are constructed of a suitable insulative material such as Plexiglas." A carrying handle 180 is connected to flange 176 to facilitate carrying the spool 158. The end flange 176 isshown both in FIGS. and 12. This flange 176 is constructed of an electrically conductive material, preferably stainless steel, and has a pair of spiral grooves 182 and 184 in its inner face 186 that wind inwardly to hub 156 (see FIGS. 12 and 13). Mounted in the spiral groove 184 is an electrode 188 similar to electrode 30 described above, that in the exemplification takes the form of a platinum-plated titanium screen. The bottom of groove '184 is insulated at 187, so as to electrically insulate the electrode screen 188 from the stainless steel flange 176. The electrode screen is coiled or spiral in shape, following the spiral groove 184 as shown in particular in FIG. 12. Connecting means (not illustrated, but that may be in the form of a simple clip-on connector) is provided for connecting the electrode screen 188 to the positive side of a DC. source in a similar fashion as explained above.

In order to load a film strip in the spool for processing of the exposed or image areas thereon, it is merely necessary to thread the film into the spiral groove 182 until it reaches the inner end of the groove adjacent hub 156. To facilitate this threading another mating groove may be provided in the inner face of flange 174. The film strip is shown schematically in FIG. 10 at 159. It will be appreciated that when threaded into spool 158, the film strip 159 will be in close proximity to the electrode screen 188 throughout its length, and of course, the film will be arranged so that its emulsion surface is adjacent the electrode screen 188. When the film is in place in spool 158, the spool is slipped onto post 154 into the tank 152. The flange 176 acts in effect as the second electrode, as it makes electrical contact with plate which is connected to a negative D.C. source. The developer is introduced into the tank, for example, through conduit 162 under the influence of a suitable controlling means. Since negatively charged waste particles form, positive potential is applied to electrode 188 and negative potential is applied to plate 170 and thus to flange 176 to agitate the developer. The negatively charged flange 176 electrolyses the developer, causing gaseous hydrogen bubbles to flow upwardly across the emulsion surface of film strip 159. This dislodges the particulate waste particles from their initial locations adjacent the exposed or image areas'of the film. At the same time, the positively charged electrode screen 188 attracts the particles, drawing them away from their initial locations permitting additional, fresh developer access to the image areas. The remainder of the process is essentially the same as that described above in conjunction with FIGS. 7 and 8.

This embodiment of the invention as shown and described in conjunction with FIGS. 10-13 offers the same advantages as mentioned above. It permits a film strip to be processed under the influence of electrophoretic and electrolytic agitation. Further, film strips of the lengths I am able to process in wound form in spool 158 (e.g., 5 feet in length and 36 to 40 inches in width) previously necessitated large trays and process sinks covering a length of approximately 15 feet of processing area. By the present invention however, the tank 152 need merely be approximately 8 inches in diameter. It will be apparent to those skilled in the art that color film may be processed by tank 152 in a manner as explained in conjunction with FIG. 9 above.

While I have explained my invention in conjunction with the embodiments shown in the drawings, it will be appreciated that the apparatus could take other forms while still incorporating the essence of the invention. It

will occur to those skilled in the art that not only can I process black and white film and plates, but that other film types such as Anscochrome, Super Anscochrome, Ektachrome, etc., can be processed by this invention. Further, while I have shown in the preferred embodiments of the invention desired dimensions of the tanks and desired magnitudes of voltages applied to the electrodes, these dimensions and magnitudes are dependent upon the photographic element being developed and the type of developer being used. Therefore, it will be understood that I can vary the tank size, as the photographic elements and developers are varied, and that the tank may be enlarged to accommodate multiple photographic plates. It will also be understood that other various substitutions or changes in form and details of the devices and in their operation may be made by those skilled in the art without departing from the true spirit and scope of the invention. It is accordingly desired that the appended claims shall not be limited to the specific details of the invention.

1 claim:

1. Apparatus for processing photographic elements having an emulsion layer with exposed areas, comprismg:

a processing tank having means for holding a developer fluid and for receiving a photographic element with an emulsion surface in immersion contact with the developer whereby negatively charged waste particles are produced at image sites of the emulsion surface as the photographic element undergoes development processing;

first electrode means located adjacent an end of the photographic element and adapted for connection to a negative direct current source for electrolyzing the developer and releasing hydrogen bubbles in a uniform stream directed adjacent and parallel to the emulsion surface; the function of said bubbles being to gently dislodge the negatively charged waste particles produced at said image sites; and

second electrode means located adjacent the emulsion surface of the photographic elementand adapted for connection to a positive direct current source for attracting the dislodged negatively charged waste particles away from said emulsion surface whereby developer is continually refreshed in the neighborhood of the emulsion surface at said image sites.

2. Apparatus for processing photographic elements having an emulsion layer with exposed areas, comprising:

a processing tank having means for receiving a photographic element with an emulsion surface in contact with a developer whereby negatively charged waste particles are released from the emulsion surface of the photographic element;

first electrode means located adjacent an end of the photographic element and adapted for connection to a negative direct current source for electrolyzing the developer and releasing hydrogen bubbles that dislodge the negatively charged waste particles;

second electrode means located adjacent the emulsion surface of the photographic element and adapted for connection to a positive direct current source for attracting the dislodged negatively charged waste particles whereby fresh developer is continually able to reach the emulsion surface of the photographic element; and

wherein the first electrode means comprises an electrode plate mounted on a first wall of the processing tank and includes a raised ridge thereon having its edge located in a plane extending parallel and in close adjacency to the emulsion surface of the photographic element whereby the hydrogen bubbles are released from said edge and rise generally in said plane.

3. The apparatus of claim 2 wherein said second electrode means comprises a generally flat screen mounted on a second wall of the processing tank and being located within a range of l 16 to 1% inches from the emulsion surface of the photographic element.

4. Apparatus for processing photographic elements having an emulsion layer with exposed areas, comprisa processing tank having means for receiving a photographic element with an emulsion surface in contact with a developer whereby negatively charged waste particles are released from the emulsion surface of the photographic element; first electrode means located adjacent an end of the photographic element and adapted for connection to a negative direct current source for electrolyzing the developer and releasing hydrogen bubbles that dislodge the negatively charged waste particles;

second electrode means located adjacent the emulsion surface of the photographic element and adapted for connection to a positive direct current source for attracting the dislodged negatively charged waste particles whereby fresh developer is continually able to reach the emulsion surface of the photographic element; and

wherein said photographic element receiving means includes a spool having a pair of end flanges for receiving photographic film strips, said second electrode means being mounted in said spool between said pair of end flanges in a spiral groove.

5. The apparatus of claim 4 wherein said first electrode means includes an electrode plate mounted on the bottom wall of said processing tank, with the lower end flange of said spool being electrically conductive and adapted for electrical connection with said electrode plate.

6. Apparatus for processing exposed photographic elements comprising:

a processing tank;

means for mounting a photographic element having an exposed emulsion surface in said processing tank;

means for introducing developer into said processing tank;

means for introducing fixer into said processing tank;

means for introducing water into said processing tank;

drain means for emptying said processing tank;

means for operating said developer introducing means, said fixer introducing means, said water introducing means and said drain means in timed sequence thereby to process the exposed photographic element completely while it is in said processing tank; and

electrical agitation means for gently dislodging and removing particulate waste products from the vicinity of the exposed emulsion surface of the photographic element while the developer is in said processing tank.

7. The apparatus of claim 6 wherein said electrical agitation means includes first and second electrodes connectible respectively to the positive and negative terminals of a direct current supply, and positioned so that the developer within said processing tank is agitated gently in the vicinity of developing image areas of the emulsion surface by a stream of bubbles released by electrolytic action at said second electrode and by electrophoretic action at the first electrode relative to development waste product particles dislodged from said emulsion surface by said bubbles. 

2. Apparatus for processing photographic elements having an emulsion layer with exposed areas, comprising: a processing tank having means for receiving a photographic element with an emulsion surface in contact with a developer whereby negatively charged waste particles are released from the emulsion surface of the photographic element; first electrode means located adjacent an end of the photographic element and adapted for connection to a negative direct current source for electrolyzing the developer and releasing hydrogen bubbles that dislodge the negatively charged waste particles; second electrode means located adjacent the emulsion surface of the photographic element and adapted for connection to a positive direct current source for attracting the dislodged negatively charged waste particles whereby fresh developer is continually able to reach the emulsion surface of the photographic element; and wherein the first electrode means comprises an electrode plate mounted on a first wall of the processing tank and includes a raised ridge thereon having its edge located in a plane extending parallel and in close adjacency to the emulsion surface of the photographic element whereby the hydrogen bubbles are released from said edge and rise generally in said plane.
 3. The apparatus of claim 2 wherein said second electrode means comprises a generally flat screen mounted on a second wall of the processing tank and being located within a range of 1/16 to 1 1/2 inches from the emulsion surface of the photographic element.
 4. Apparatus for processing photographic elements having an emulsion layer with exposed areas, comprising: a processing tank having means for receiving a photographic element with an emulsion surface in contact with a developer whereby negatively charged waste particles are released from the emulsion surface of the photographic element; first electrode means located adjacent an end of the photographic element and adapted for connection to a negative direct current source for electrolyzing the developer and releasing hydrogen bubbles that dislodge the negatively charged waste particles; second electrode means located adjacent the emulsion surface of the photographic element and adapted for connection to a positive direct current source for attracting the dislodged negatively charged waste particles whereby fresh developer is continually able to reach the emulsion surface of the photographic element; and wherein said photographic element receiving means includes a spool having a pair of end flanges for receiving photographic film strips, said second electrode means being mounted in said spool between said pair of end flanges in a spiral groove.
 5. The apparatus of claim 4 wherein said first electrode means includes an electrode plate mounted on the bottom wall of said processing tank, with the lower end flange of said spool being electrically conductive and adapted for electrical connection with said electrode plate.
 6. Apparatus for processing exposed photographic elements comprising: a processing tank; means for mounting a photographic element having an exposed emulsion surface in said processing tank; means for introducing developer into said processing tank; means for introducing fixer into said processing tank; means for introducing water into said processing tank; drain means for emptying said processing tank; means for operating said developer introducing means, said fixer introducing means, said water introducing means and said drain means in timed sequence thereby to process the exposed photographic element completely while it is in said processing tank; and electrical agitation means for gently dislodging and removing particulate waste products from the vicinity of the exposed emulsion surface of the photographic element while the developer is in said processing tank.
 7. The apparatus of claim 6 wherein said electrical agitation means includes first and second electrodes connectible respectively to the positive and negative terminals of a direct current supply, and positioned so that the developer within said processing tank is agitated gently in the vicinity of developing image areas of the emulsion surface by a stream of bubbles released by electrolytic action at said second electrode and by electrophoretic action at the first electrode relative to development waste product particles dislodged from said emulsion surface by said bubbles. 